A labor and delivery nurse shares how her twin daughter's jaw healed due to in-utero pressure from her sister Ashley Vega is a writer-reporter at PEOPLE. She has been working at PEOPLE since 2024.

Therein, you have a womb with two embryos of different ages. This process is called superfetation. These are not fraternal twins, fraternal embryos are the same age. Can two sperm fertilize one ...

Marmoset pregnancies generally produce fraternal twins. During gestation ... suggesting that the in utero exchange of nonhematopoietic stem cells is common during marmoset development.

What's the meaning of fraternal twins? Fraternal twins come from two separate fertilized eggs that develop in the womb at the same time, each with their own placenta and amniotic sac. Like any ...